retrocomputing and fpg's 18 or other odd size bits

ben bfranchuk at
Wed Apr 11 18:45:40 CDT 2018

On 4/11/2018 4:16 PM, Torfinn Ingolfsen via cctalk wrote:
> Since you brought it up
> On Wed, Apr 11, 2018 at 11:48 PM, ben via cctalk <cctalk at> wrote:
>> The FREE fpga development software is only under windows.
> Free alternatives exist (and can only get better coverage with time)

Does NOT support my FPGA. I am using the FPGA for all the heavy lifting
of testing my cpu design so in time it can be used for other things. The 
real design is a microcode 2901 cpu about 1976 ish, with 256x8 70 ns 
proms. Modern 22V10's will be used as 'prom' and 'glue' logic, but alas 
that software and GAL programmer still are windows only.

It is a similar feel to the 16 bit computers other than the PDP 11,
and same cycle times as core of that era. 1.3 us for operate and 2.6 us 
memory operations. 18 bits is just about right for a 'small' computer
size and operands and front panel. Disk I/O will be fake devices of 9 
bit characters on a SD card.

Now I need to hit the web for some good programing books from the
1970's era so I finalize the I/O and memory map of the computer and
fine tune the instruction set.

Yes I know the FPGA card can run faster,but not with 1976 speeds.

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